Transcript The Day After Tomorrow

Real Science or
Reel Science?
Presented by:
Lis Cohen
Meteorology Graduate Student
National Science Foundation WEST Fellow
University of Utah
Outline
• Can New York City go from hot to freezing in a
few hours? Does climate change happen that
fast?
• Is it true that the North Atlantic current could shut
down?
• Is it realistic that a giant wave could hit New York
City because of a hurricane?
• If air from the upper atmosphere is brought
down to the surface in a hurricane, will it freeze
us?
• Can big storms create giant tornados in LA?
Can New York City go from hot to
freezing in a few hours? Does
climate change happen that fast?
• Climate change does not happen that fast
or dramatically!
– Ocean temperature changes take a
long time
• Large heat capacity
• Large ocean volume
– Ocean currents could change over
many years
Is it true that the North Atlantic
current could shut down?
The ocean surface transfers heat to the atmosphere!
Animation by Jack Cook (Woods Hole Oceanographic Institute)
What process could change the
ocean circulation?
Can giant hurricanes exist all
around the world?
• Clusters of thunderstorms cannot merge
together to form a continent-scale blizzard
with a calm eye over land.
• Huge storms with calm eyes happen over
the oceans not over land.
– Hurricanes or Tropical Storms
• Require that the core of the storm be over warm
ocean water
Photo: earthobservatory.nasa.gov/NaturalHazards/Arch...
If air from the upper atmosphere is brought down to the
surface in a hurricane, will it freeze us?
Closer to the Earth’s surface, the air pressure is higher than higher up in the
atmosphere. As we bring the air down to the Earth the air pressure increases.
As we apply pressure to air, air warms instantaneously!
Bring air which is -80º C from 15km (tropopause) down to the surface
1. Temperature change because of pressure changes
15km*9.8º/km(for dry air)= +147ºC
– Original temp + temp change = temp at surface
-80ºC+147ºC=67ºC
– Change to Fahrenheit
67ºC*(9/5)+32=152.6ºF
Can ice sheets melt and build
overnight?
– Ice Sheets and Glaciers
• Immense mass prevents rapid
melting of ice sheets.
– Ex. Climate quickly changed at the
end of last ice age
» Decades and centuries later
the ice sheets and deep ocean
adjusted. (NSIDC)
• The major ice sheets over North
America at the peak of the last
ice age took tens of thousands
of years to build up. (NASA)
http://daily.greencine.com/archives/day-after-tomorrow.jpg
Is it realistic that a giant wave could hit
New York City because of a hurricane?
http://www.movie-vault.com/images/news/rainyorkbig.jpg
http://i.a.cnn.net/cnn/2004/SHOWBIZ/Movies/05/27/
day.tomorrow/story.day.tomorrow.jpg
Tsunami vs. Storm Surge
TSUNAMI
• Arrives quickly as a large wave
or movement of water onto the
shore
• Causes
– Earthquakes
– Submarine Landslide
– Calving of glaciers
• Tend to be localized
events
• Antarctic ice collapse
would not likely reach
the US.
STORM SURGE
• Arrives as a rise in water in a
period of a few hours.
• Causes
– Low pressure of a storm
lifts up the surface of the
ocean (only a few feet)
– Winds pushing water onto
the land
• Wind speeds would
need to be at least
twice the speed of
sound (1200 mph) to
create a 300ft storm
surge.
Data from: Dr. Jeffrey M. Masters
Can big storms create giant
tornados in LA?
Ingredients for a tornado:
• Unstable Atmosphere
• Moisture
• Vertical wind sheer
Los Angeles
• Stable atmosphere
• Little moisture
What process could most likely change the climate?
More moisture in
the air
Warmer climate
Circulation slows down
and changes
More evaporation at the equator
More moisture can
be held in the air
Water does not sink in the northern latitudes
Melting Glaciers
Ocean is not as
salty and dense
More freshwater
in the ocean
More rain
at higher
latitudes
Conclusion
• Climate change can not happen as quickly as
the movie portrays.
• Scientists’ prediction models show a possible
slow down and/or adjustment to the North
Atlantic current, but not a shut down.
• Tsunamis not hurricanes, create waves like in
the movie.
• If air from the upper atmosphere is brought
down to the surface, we will have warm
temperatures.
• Giant tornados in Los Angeles are very unlikely.
Questions?
How fast can the atmosphere and
ocean respond to each other?
• El Nino– Winds weaken and
ocean responds
• This change can
happen on the time
scale of weeks.
• Atmosphere
– Readjusts within days
ex. Moving jet streams
How does ocean circulation affect local climates?
Answer: Heat release locations are warmer!
Warm surface current- Less Dense
Cold deep water current–More Dense
Salty water anywhere- More Dense
Intergovernmental Panel on Climate Change (IPCC), "Climate Change 2001: The Scientific Basis"
What directions do warm and cold
water currents travel?
Animation by Jack Cook (Woods Hole Oceanographic Institute)
What is happening with ice shelves
today?
• Today shifting climate
– Antarctic Peninsula
the ice shelves are no
longer stable. The
northern most limit for
ice shelves has
moved south over the
past two decades by
about 100 miles.
(NSIDC)
http://images.amazon.com/images/P/B0007PALRU.01.LZZZZZZZ.jpg
Three Glaciers Retreating
Denver Glacier in Recession,
Alaska, British Columbia
• Source: C.L. Andrews. 1912, 1938. Denver Glacier:
1912
1938
From
the Glacier Photograph Collection . Boulder, CO:
National Snow and Ice Data Center. Digital Media;
Marion T. Millett. 1958. Denver Glacier: From the Glacier
Photograph Collection . Boulder, CO: National Snow and
Ice Data Center. Digital Media.
How do we know about past
climates?
• Ice sheets reveal
annual layers
– history of precipitation
and air temperatures
100,000 years in the
past.
•
Photo by: Lonnie Thompson, Ohio State University
Flash Freezing
• The superstorm sucks vast quantities of frigid upper atmospheric air
down to the surface, flash freezing any living thing caught outside.
However, any graduate of a high school physics course could tell
you that the air would warm on its descent in response to the
requirements of the Ideal Gas Law, and would never be able to flash
freeze anything. One scientist in the movie does remember his high
school physics and asks, "But wouldn't the air warm as it
descends?" But the senior scientist replies, "No, it's moving too
fast!" Sorry, guy, but the Ideal Gas Law applies no matter how fast
the air is moving. If you were on my thesis committee, I'd kick you
off.
• by Dr. Jeffrey M. Masters
Chief Meteorologist, The Weather Underground, Inc.
Storms flowing opposite directions
• The superstorm is shown in many scenes
rotating clockwise, and in other scenes counterclockwise. Oops, all large-scale storm systems
in the Northern Hemisphere must rotate counterclockwise, thanks to one of the laws of physics
on a rotating planet called the Coriolis force.
– by Dr. Jeffrey M. Masters
Chief Meteorologist, The Weather Underground, Inc.
In a warmer earth scenario
– Ocean level will rise because as liquid water
is heated it expands.
– The ice caps melt and add water to the
system.
•
http://www.whoi.edu/institutes/occi/images/occi_abrclimate_jk_lev_en.gif
Temperature and Ice Accumulation
vs. Time